Firefly Green Fuels converts sewage sludge into sustainable aviation fuel (SAF) using hydrothermal liquefaction, addressing both waste management and aviation decarbonization needs. The UK-based company processes sludge from water utilities in a high-pressure reactor, yielding biochar for agricultural fertilizer and bio-crude refined into jet fuel compatible with existing aircraft engines.
James Hygate, Firefly CEO, notes that sewage offers an abundant, low-value feedstock abundant globally, with the UK alone generating 53 million tonnes of untreated sludge annually from 8,500 wastewater treatment works. Current disposal via agricultural spreading faces potential bans due to environmental concerns like river pollution, which has seen a 37% rise in incidents.
The FIREFLY project, funded by the UK Department for Transport’s Green Fuels, Green Skies competition, validated the process through independent tests confirming bio-kerosene quality matches fossil jet fuel standards. Ongoing evaluations occur at the DLR Institute of Combustion Technology and Washington State University.
Firefly plans a first-of-its-kind UK plant this decade, starting with a pilot at Haltermann Carless refinery supplied by container-sized units at treatment works. Discussions with a major metropolitan area suggest the process could fuel 80% of its international airport flights with SAF. A November 2024 memorandum with Brazilian firm Sanepar supports global rollout via a hub-and-spoke model, targeting 100,000 tonnes of crude equivalent annually for initial operations.
This pathway complements approved SAF methods like HEFA, leveraging biogenic waste to scale production amid demand exceeding current capacities.